1. Field of Invention
This invention relates to firearm barrels and components, specifically a method for improving accuracy and extending the useful life of the firearm.
2. Description of Prior Art
Many tempering processes for treating metals and other materials are known. Controlled thermal cycling treatments have been applied to various metals for a number of years.
One of the benefits of tempering is stress relief. There is always some stress in the metal as a result of heat treating, forming or manufacturing. Additional stress is imparted to the metal from machining and finishing operations.
The most common method for stress relief of firearm barrels is conventional heat treating. Typical stress relief heat treating is the uniform heating of a structure or a portion thereof to a suitable temperature below the transformation range and holding at this temperature for a predetermined period of time followed by uniform cooling.
Conventional heat treating however can cause distortion and damage to coatings and other surface treatments. Some residual stresses however appear to remain even after this stress relieving operation.
This invention relates a new method to promote stress relief by deep cryogenic tempering which does not cause any damage to the firearm barrel, coatings, surface treatments or components.
The most common items to receive some type of sub-ambient tempering treatment have been those in the tool and die industry. It has been found that sub-ambient treatment (freezing to -120 F.) improves the wear resistance and stress relief of these items. The improvement is greatly increased by deep cryogenic treatment. Deep cryogenic treatment is performed at -300 F.
Sub-ambient treatments in the past utilized a liquid process which in some cases will cause thermal shock. This is detrimental as it will add stress to the structure.
This invention will treat firearm barrels and components to greatly improve the stress relief and to increase wear resistance without the danger of thermal shock.